How little the position moves
The full spread across more than a hundred years is about one and one third degrees. Put another way, someone born on this date in 1934 and someone born on it in 2034 have Suns close enough together that they would be read as occupying the same place in the sign. Birthdays are far better markers of solar position than the vagueness around them suggests.
The reason is arithmetic rather than coincidence. A tropical year is about three hundred and sixty five and a quarter days, so each common year the Sun arrives at a given date a quarter of a day late, and after three of those a leap day resets the accumulated lag. The date and the orbit are held together by that correction, and the position on any fixed date wobbles inside a narrow band instead of sliding away from it.
Inside the second decan
Ten to twenty degrees of Libra is the sign's second decan, and in every year covered here noon on 4 October has been inside it. In the Chaldean sequence that band is assigned to Saturn, layered underneath the Venus rulership that covers the whole sign.
Tradition makes something of that pairing. Venus is read as the principle of relation and proportion, Saturn as the principle of limit and structure. The middle third of Libra is where readings place the sign's more exacting side, the part that holds a standard rather than simply seeking agreement. It is a claim about a ten degree band, and it is the layer that distinguishes this birthday from one in the opening or closing third of the same sign.
What a shared date does not give you
Everyone born on 4 October in a given year shares a solar degree to within a fraction. Almost nothing else follows. The Moon covers something like thirteen degrees in a day and can cross a sign boundary while doing it, so two people with this birthday may well have Moons in different signs, and the Moon carries much of what a reading says about temperament and response.
The rising sign depends on the hour and on how far north or south the birth happened. A whole zodiac passes over the horizon in a day, so this date leaves that placement completely open. Since the ascendant fixes where every planet falls among the houses, the same set of planets can be read in twelve different arrangements on the same birthday.
What Libra means in the tradition
Libra is the cardinal sign of the air triplicity, ruled by Venus. It begins at the autumn equinox, the moment when day and night are equal, which is the origin of the balance imagery rather than any observed trait of the people born during it. Air signs are read as working through comparison, and the cardinal mode as initiating, so the sign is described as the one that opens questions of proportion and fairness.
All of that is interpretation resting on a measured longitude. The measurement is checkable and the reading is a tradition, and the two are worth keeping apart. Knowing the degree and the decan at least tells you which part of the tradition is being applied to you.
Questions people ask about this
Is 4 October always Libra?
Yes, in every year from 1930 to 2035. The date falls around ten days after the equinox crossing and nearly three weeks before the Scorpio one, so there is no year in that span where it lands in an adjacent sign.
What degree of Libra is a 4 October birthday?
Between roughly ten and a third and eleven and two thirds at noon, depending on the year. Your own figure also depends on the hour and the birthplace, both of which the widget above takes into account.
Why is the degree worth knowing?
It decides which aspects the Sun makes to other planets and which house it occupies once a birth time is supplied. A sign name alone is a thirty degree band, which is too coarse for either of those.
Which decan applies to this date?
The second decan of Libra, running from ten to twenty degrees. Under the Chaldean order that band is given to Saturn, which sits alongside Venus as the ruler of the sign as a whole.
Do people born on the same day have similar charts?
Only in the slow moving parts. The Sun and the outer planets match, the Moon often does not, and the rising sign and house layout usually differ entirely because they depend on the hour and the place.
Does a later birth hour change the sign?
Not on this date. The Sun moves about a degree a day, so a birth at midnight and one at midday differ by around half a degree and both sit firmly inside Libra.